This invention relates to an apparatus for hyperthermia surgery in a patient using a magnetic resonance imaging system to effect guiding and control of the heating source.
The excision of tumours by hyperthermia is known. Thus tumours and other masses to be excised can be heated above a predetermined temperature of the order of 55xc2x0 C. so as to coagulate the portion of tissue heated. The temperature range is preferably of the order of 55 to 65xc2x0 C. and does not reach temperatures which can cause ablation of the tissue.
One technique for effecting the heating is to insert into the mass concerned an optical fiber which has at its inserted end an element which redirects laser light from an exterior source in a direction generally at right angles to the length of the fiber. The energy from the laser thus extends into the tissue surrounding the end or tip and effects heating. The energy is directed in a beam confined to a relatively shallow angle so that, as the fiber is rotated, the beam also rotates around the axis of the fiber to effect heating of different parts of the mass at positions around the fiber. The fiber can thus be moved longitudinally and rotated to effect heating of the mass over the full volume of the mass with the intention of heating the mass to the required temperature without significantly affecting tissue surrounding the mass.
At this time the fiber is controlled and manipulated by a surgeon with little or no guidance apart from the knowledge of the surgeon of the anatomy of the patient and the location of the mass. It is difficult therefore for the surgeon to effect a controlled heating which heats all of the tumour while minimizing damage to surrounding tissue.
It is of course well known that the location of tumours and other masses to be excised can be determined by imaging using a magnetic resonance imaging system. The imaging system thus generates for the surgeon a location of the mass to be excised but there is no system available which allows the surgeon to use the imaging system to control the heating effect. In most cases it is necessary to remove the patient from the imaging system before the surgery commences and that movement together with the partial excision or coagulation of some of the tissue can significantly change the location of the mass to be excised thus eliminating any possibility for controlled accuracy.
It is also known that magnetic resonance imaging systems can be used by modification of the imaging sequences to determine the temperature of tissue within the image and to determine changes in that temperature over time.
U.S. Pat. No. 4,914,608 (LeBiahan) assigned to U.S. Department of Health and Human Services issued Apr. 3, 1990 discloses a method for determining temperature in tissue.
U.S. Pat. No. 5,284,144 (Delannoy) also assigned to U.S. Department of Health and Human Services and issued Feb. 8, 1994 discloses an apparatus for hyperthermia treatment of cancer in which an external non-invasive heating system is mounted within the coil of a magnetic resonance imaging system. The disclosure is speculative and relates to initial experimentation concerning the viability of MRI measurement of temperature in conjunction with an external heating system. The disclosure of the patent has not led to a commercially viable hyperthermic surgery system.
U.S. Pat. Nos. 5,368,031 and 5,291,890 assigned to General Electric relate to an MRI controlled heating system in which a point source of heat generates a predetermined heat distribution which is then monitored to ensure that the actual heat distribution follows the predicted heat distribution to obtain an overall heating of the area to be heated. Again this patented arrangement has not led to a commercially viable hyperthermia surgical system.
An earlier U.S. Pat. No. 4,671,254 (Fair) assigned to Memorial Hospital for Cancer and Allied Diseases and issued Jun. 9, 1987 discloses a method for a non surgical treatment of tumours in which the tumour is subjected to shock waves. This does not use a monitoring system to monitor and control the effect.
It is one object of the present invention, therefore, to provide an improved method and apparatus for effecting controlled surgery by hyperthermia.
According to a first aspect of the invention there is provided a method for effecting surgery by hyperthermia comprising:
providing a heat source arranged to apply heat to a part of a patient on whom the surgery is to be effected;
operating a non-invasive detection system to generate a series of output signals over a period of time representative of temperature in the part as the temperature of the part changes during that time;
identifying a plurality of locations in the part to be heated to a required hyperthermic temperature;
using the output signals to monitor the temperature at the locations as the temperature changes over the period of time;
for each location, controlling the heat source to effect heating of an area of the part adjacent the location;
and, for each location, continuing the heating at the respective area until the temperature at the location reaches the required hyperthermic temperature as monitored whereupon the heating in the area is halted.
Preferably the heat source is controlled by controlling an amount of heat generated thereby and by controlling a selected area of the part to which the heat is applied.
Preferably the monitored locations are arranged at an outer periphery of a volume to be heated to the required hyperthermic temperature.
Preferably the method includes identifying the locations at the outer periphery of the volume, generally a tumor, to be heated from a preliminary series of signals from the non-invasive detection system.
Preferably the heat source is provided on an invasive probe inserted into the part and wherein the control of the heat source is effected by moving the probe. However other non-invasive but directional heating techniques can be used such as ultra-sound and other radiations.
Preferably the heat source is provided on an invasive probe and is arranged to cause heating in a predetermined direction relative to the probe and wherein the control of the heat source is effected by moving the probe to alter the direction.
Preferably the heat source comprises a laser, an optical fiber for communicating light from the laser, a mounting for the optical fiber allowing invasive insertion of an end of the fiber into the part of the patient, a light directing element at an end of the fiber for directing the light from the laser to a predetermined direction relative to the fiber and a position control system for moving the end of the fiber.
Preferably there is provided a cannula through which the fiber is inserted, the cannula having an end which is moved to a position immediately adjacent but outside the part to be heated and the fiber having a rigid end portion projecting from the end of the cannula into the part.
According to a second aspect of the invention there is provided an apparatus for effecting surgery by hyperthermia comprising:
a heat source arranged to apply heat to a part of a patient on whom the surgery is to be effected;
a non-invasive detection system arranged to generate a series of output signals over a period of time representative of temperature in the part as the temperature of the part changes during that time;
and a control system comprising:
a first means arranged to identify a plurality of locations in the part to be heated to a required hyperthermic temperature;
a second means arranged to use the output signals to monitor the temperature at the locations as the temperature changes over the period of time;
and a third means arranged to control the heat source to effect heating of an area of the part adjacent each location;
the control system being arranged in response to said temperatures at the locations to operate the third means to control the selection of the area to which heat is applied and to control the amount of heat applied to the area.
Preferably the control system includes a first control for controlling an amount of heat generated by the heat source and a second control for moving the heat source to effect heating at a selected area of the part to which the heat is applied.
Preferably the heat source comprises: an optical fiber having an inlet end and an outlet end; a laser source for supplying light energy into the fiber at the inlet end; a light deflector at the outlet end for directing the light in a beam at an angle to a longitudinal axis of the fiber at the outlet end such that rotation of the fiber about the axis causes the beam to rotate about the axis; and a rigid elongate cannula arranged for insertion to a position at the part of the patient; the cannula having a bore arranged for receiving a portion of the fiber adjacent the outlet end in sliding engagement therein such that the end can pass through the cannula into engagement with the part of the patient.
Preferably the third means of the control system comprises a drive assembly for causing a first longitudinal movement of the fiber relative to the cannula along its length and for causing a second rotational movement of the fiber about its axis.
Preferably there is provided a mounting for the drive assembly for supporting the drive assembly exteriorly of the cannula and wherein the fiber has a reinforcing sleeve member surrounding and attached to a portion of the fiber so as to extend from the drive assembly to the outlet end, the sleeve member holding the fiber against lateral bending during said longitudinal movement and against torsional twisting during said rotational movement and the sleeve member being arranged to extend through the cannula.
Preferably the sleeve includes at least a portion which is integrally molded from a fiber reinforced polymer.
Preferably the sleeve includes a first portion at the outlet end which is formed of a first material, such as glass which is substantially rigid to rigidly support that portion of the fiber projecting in cantilever manner beyond the end of the cannula and a second portion connected to and extending from the first portion to the drive assembly, the second portion being formed of a second material such as liquid crystal polymer which is stiff but less rigid than the first portion to allow some flexing when the fiber is inserted into the cannula. In another arrangement, the sleeve can be wholly formed from a material which allows the necessary stiffness but does not have the brittleness of for example glass.
Preferably the reinforcing sleeve includes an engagement portion attached thereto for engaging the drive assembly including a portion of polygonal cross-section for engaging into a drive collar of corresponding cross-section of the drive assembly for driving rotational movement of the fiber and including a shoulder section for engaging against a drive member of the drive assembly for driving longitudinal movement of the fiber.
Preferably the non-invasive detection system comprises a magnetic resonance imaging system including a magnet to generate a magnetic field for the imaging system and an antenna for detecting radio frequency signals from the part of the patient; and wherein the third means of the control system includes a member located within and arranged to be moved within the magnetic field and a motor for driving movement of the member, the motor including no ferro-magnetic components such that it is usable in the magnetic field and the motor and a drive coupling thereto being shielded by a surrounding conductor to prevent interference with the radio frequency signals.
Preferably the third means of the control system includes a driven member rotatable about an axis and a reciprocating drive element arranged to cause a ratcheting movement of the driven member.
Preferably the reciprocating drive element comprises a piezo-electric motor.
Preferably one driven member includes a sleeve arranged to receive the fiber therethrough and the fiber and sleeve are non circular or polygonal in shape such that rotation of the member causes rotation of the fiber about the axis while allowing longitudinal sliding movement of the fiber relative to the sleeve.
Preferably one driven member has a female threaded bore therein and wherein the fiber has attached thereto a screw engaging the bore such that rotation of the driven member about the axis causes the screw to effect movement of the fiber longitudinally along the axis.
According to a third aspect of the invention there is provided an apparatus comprising:
a magnetic resonance imaging system arranged to generate an image from a sample and including a magnet to generate a magnetic field and an antenna for detecting radio frequency signals from the sample;
a member located within and arranged to be moved within the magnetic field;
and a motor having a drive coupling thereto for driving movement of the member, the motor including a reciprocating element for generating a motive force for the motor;
the motor including no ferro-magnetic components such that it is usable in the magnetic field and the motor and the drive coupling being shielded by a surrounding conductor to prevent interference with the radio frequency signals.
According to a fourth aspect of the invention there is provided an apparatus for laser surgery on a part of a patient comprising:
an optical fiber having an inlet end and an outlet end;
a laser source for supplying light energy into the fiber at the inlet end;
a light deflector at the outlet end for directing the light in a beam at an angle to a longitudinal axis of the fiber at the outlet end such that rotation of the fiber about the axis causes the beam to rotate about the axis;
a rigid elongate cannula arranged for insertion into the part of the patient;
the cannula having a bore arranged for receiving a portion of the fiber adjacent the outlet end in sliding engagement therein such that the end can pass through the cannula into engagement with the part of the patient;
a drive assembly for causing a first longitudinal movement of the fiber relative to the cannula along its length and for causing a second rotational movement of the fiber about its axis;
the fiber having a reinforcing sleeve member surrounding and attached to a portion of the fiber adjacent the outlet end, the sleeve member holding the fiber against lateral bending during said longitudinal movement and against torsional twisting during said rotational movement.
According to a fifth aspect of the invention there is provided a method for effecting surgery comprising:
providing a radiation source arranged to apply radiation to a part of a patient on whom the surgery is to be effected, the radiation being arranged to cause ablation of the part;
operating a non-invasive detection system to generate a series of output signals over a period of time representative of the effect of the radiation in the part as the radiation affects the part during that time;
identifying a plurality of locations in the part to ablated;
using the output signals to monitor the effect of the radiation at the locations as the radiation affects the part over the period of time;
for each location, controlling the radiation source to effect ablation of an area of the part adjacent the location;
and, for each location, continuing the radiation at the respective area until the effect of the radiation at the location reaches the required ablation as monitored whereupon the radiation in the area is halted.
It will be noted therefore that the ablation of the part can be effected by other forms of controlled directional radiation other than heat. The radiation is directed to the tip of the probe and controlled in direction and location while the effect of the radiation is monitored. Various forms of radiation can be used provided they are directional and controllable and effect ablation of the part.
Preferably the monitored locations define an outer periphery of a volume such as a tumour to be ablated.
Preferably the method includes identifying the outer periphery of the volume to be ablated from a preliminary series of signals from the non-invasive detection system and monitoring the effect of the radiation over the full area defined by the outer periphery.
Preferably the radiation source is provided on an invasive probe inserted into the part and wherein the control of the radiation source is effected by moving the probe.